Utilizing its properties, a fluorine gas has been employed in an etching process or a cleaning process in the field of electronic industry or has been employed for fluorination of inorganic compounds or organic compounds in recent years. The fluorine gas, however, is a combustion supporting gas having extremely strong oxidizing properties, and exhibits high toxicity and corrosive properties, so that care must be taken in handling. Further, it is known that purification by distillation in the production of a fluorine gas is difficult.
As a method to feed a fluorine gas safely, a “halogen generator” that generates a fluorine gas by heating a fluorine compound has been proposed (see, for example, U.S. Pat. No. 5,363,396).
In SU-A-1432001, a process for producing a purified fluorine gas using MnF4 is disclosed. More specifically, a process wherein MnF4 formed by the reaction of MnF3 with a fluorine gas in a stream of a fluorine gas at 450 to 650° C. is sublimated, then the sublimated MnF4 is solidificated at a temperature of not higher than 70° C. to obtain MnF4, and the resulting MnF4 is heated to a temperature of 70 to 300° C., that is, a process for producing a purified fluorine gas in accordance with the reaction formula MnF4→MnF3+½F2 is described.
In this process, however, there are problems that synthesis of MnF4 is infeasible unless a complicated apparatus capable of performing thermal sublimation and capture of the sublimated MnF4 is used, and mass production is difficult because steps of sublimation and solidification must be carried out.
In order to produce MnF4 without going through the steps of sublimation and solidification, the present inventors attempted a process for synthesizing MnF4 through MnF3 by allowing MnF2 to react with a fluorine gas (reaction formula: MnF2+F2→MnF4) . However, if the MnF2 is only brought into contact with a fluorine gas to perform reaction, MnF2 is fused like glass and the reaction does not proceed, so that it is difficult to produce MnF4. If the pressure is raised, the reaction to form MnF4 proceeds, but a pressure-resistant container capable of using a fluorine gas at high temperatures and high pressure is very expensive, and as a result, the synthesized MnF4 becomes expensive. On this account, development of a process capable of performing the reaction at a temperature and a pressure as low as possible has been desired.